1. Field of the Invention
The present invention relates to a silicon carbide semiconductor device and a method for manufacturing the silicon carbide semiconductor device, more particularly, a silicon carbide semiconductor device having a contact electrode and a method for manufacturing such a silicon carbide semiconductor device.
2. Description of the Background Art
In recent years, a silicon carbide substrate has begun to be used for manufacturing of a semiconductor device. Silicon carbide has a band gap larger than that of silicon. Hence, a semiconductor device employing a silicon carbide substrate advantageously has a high breakdown voltage, low on-resistance, and properties less deteriorated in a high temperature environment.
For example, Japanese Patent Laying-Open No. 7-99169 discloses a method for forming an electrode that makes ohmic contact with an n type silicon carbide substrate. According to this method, a NiSi (nickel silicide) alloy layer, which contains Ni (nickel) at a composition ratio of 33 atomic % to 67 atomic %, is formed on the n type silicon carbide substrate, and thereafter heat treatment is provided thereto, thereby forming an electrode that makes ohmic contact with the n type silicon carbide substrate.
Although the electrode manufactured using the method described in Japanese Patent Laying-Open No. 7-99169 can make ohmic contact with the n type silicon carbide substrate, the electrode has a large contact resistance for a p type silicon carbide substrate.